I bought a 192t and a 200t in recent years, both used: the 200t from a CT pawn shop and the 192t from a tree guy who was in my local Stihl store buying a newer saw, and planned to keep the 192t. I paid him by check IIRC, $200.
At the time I wasn't really sure of the actual value but it seemed like a fair to slightly high price. The 200t is a way better saw, but the 192t is alright if one can't get hold of a 200t.
I agree your prices are on the high side of what people are willing to pay, and the Stihls you have are pro saws for a specialty market.
See if you can interest local tree businesses or local small arborists in those saws for slightly less $.
I'd buy another 200t in a heartbeat.
Good luck. Post back results.